There are a lot of ways of expressing your feelings to her. If
you are the shy type, drop her hints along the way. For eg, be more
attentive and caring to her needs, help her do things or buy
things, ask her out more often, be there if she needs someone, or
to the extent of "defend" her when she is harmlessly bullied by
friends. Don't worry about your friends teasing you, coz basically
that's your idea of letting her know.
Listening, IMHO, is a skill that most guys lack nowadays. Pay
attention to what she said, what she wants. She may like something
or whatever food. Do all the things that please her. It will show
that you actually care for her.
When to reveal your true feelings to her is up to you, but do it at
the right time. Observe her reactions and body language when you
are with her. They can be useful indications whether she has
accepted or irritated by your wooing. From there, then make the
decision.
Lastly, if you succeed, don't stop. Continue to be a gentleman and
treat her nice. A good relationship doesn't stop at the "honeymoon"
period. Remember that. Wish you luck.